The engine of a lift truck is typically located under the seat of the vehicle, and the seat needs to be removed for servicing the engine. Lift trucks have a compact structure that is adapted to travelling in narrow aisles of packed warehouses or to maneuvering in and out of rail box cars for examples. For this reason, driver seats in these lift trucks are generally as simple as possible and are often designed for removability rather than for comfort.
Because of the physical constrictions in these industrial vehicles, it has been a challenge in the past to design a seat suspension system that offers comfort to the driver as well as an easy access to the engine compartment of the vehicle. In that respect, it is known that a number of removable vehicle seats have been developed in the past and have been used with varying degrees of success. Examples of seats and seat adjustment mechanisms for industrial vehicles are illustrated and described in the following patent documents.
U.S. Pat. No. 2,043,287 issued on Jun. 9, 1936 to John M. Dorton; PA0 U.S. Pat. No. 2,466,345 issued on Apr. 5, 1949 to Nathaniel Wyeth; PA0 U.S. Pat. No. 2,685,913 issued on Aug. 10, 1954 to Brune G. Schlueter; PA0 U.S. Pat. No. 3,545,810 issued on Dec. 8, 1970 to Ralph F. Anderson et al.; PA0 U.S. Pat. No. 3,583,518 issued on Jun. 8, 1971 to Darwin Carl Bichel et al.; PA0 U.S. Pat. No. 3,827,747 issued on Aug. 6, 1974 to Austin C. Cookes; PA0 U.S. Pat. No. 3,841,696 issued on Oct. 15, 1974 to Robert T. Wagner; PA0 U.S. Pat. No. 4,005,845 issued on Feb. 1, 1977 to Carlos E. Luppi et al.; PA0 U.S. Pat. No. 4,025,108 issued on May 24, 1977 to Conard E. Leighty et al.; PA0 U.S. Pat. No. 4,026,601 issued on May 31, 1977 to John L. Dill, III et al.; PA0 U.S. Pat. No. 4,047,759 issued on Sep. 13, 1977 to D. P. Koscinski; PA0 U.S. Pat. No. 4,076,302 issued on Feb. 28, 1978 to Frank R. Sable; PA0 U.S. Pat. No. 4,168,050 issued on Sep. 18, 1979 to Marvin E. Nerem et al.; PA0 U.S. Pat. No. 4,262,958 issued on Apr. 21, 1981 to Henry J. Houseman et al.; PA0 U.S. Pat. No. 4,311,205 issued on Jan. 19, 1982 to Ronald Goodacre et al.; PA0 U.S. Pat. No. 4,312,418 issued on Jan. 26, 1982 to Udo Rittman; PA0 U.S. Pat. No. 4,359,121 issued on Nov. 16, 1982 to John S. Messner et al.; PA0 U.S. Pat. No. 4,364,602 issued on Dec. 21, 1982 to Corrado Rigazio; PA0 U.S. Pat. No. 4,429,761 issued on Feb. 7, 1984 to Louis A. Haddock, Jr. et al.; PA0 U.S. Pat. No. 4,565,407 issued on Jan. 21, 1986 to Peter F. Brautigam; PA0 U.S. Pat. No. 4,696,508 issued on Sep. 29, 1987 to Peter F. Brautigam; PA0 U.S. Pat. No. 4,884,843 issued on Dec. 5, 1989 to Delbert D. DeRees; PA0 U.S. Pat. No. 4,930,593 issued on Jun. 5, 1990 to James A. Swartzendruber et al.; PA0 U.S. Pat. No. 5,037,155 issued on Aug. 6, 1991 to David R. Holm et al.; PA0 U.S. Pat. No. 5,303,792 issued on Apr. 19, 1994 to Yutaka Shimizu; PA0 U.S. Pat. No. 5,524,721 issued on Jun. 11, 1996 to Yoshihiko Yamauchi; PA0 U.S. Pat. No. 5,524,722 issued on Jun. 11, 1996 to Robert L. Bowman; PA0 U.S. Pat. No. 5,636,884 issued on Jun. 10, 1997 to Brett G. Ladetto et al.; PA0 U.S. Pat. No. 5,720,462 issued on Feb. 24, 1998 to Cole T. Brodersen; PA0 U.S. Pat. No. 5,733,006 issued on Mar. 31, 1998 to Perry W. Woods; PA0 U.S. Pat. No. 5,797,574 issued on Aug. 25, 1998 to Stephen R. Brooks et al.; PA0 U.S. Pat. No. 5,853,221 issued on Dec. 29, 1998 to D.C. Thoman et al.; PA0 CA 1,237,971 issued on Jun. 14, 1988 to Frank W. Grigg; PA0 CA 1,242,134 issued on Sep. 20, 1988 to Roy M. Bailey; PA0 CA 2,015,353 published on Jun. 4, 1991 by Dennis J. Gryp; PA0 GB 1,202,632 issued on Aug. 19, 1970 to Georg Grammar;
It is believed that the seats and seat suspension mechanisms described in the prior art documents were designed for specific applications or for specific makes of vehicles and are hardly adaptable to different models of lift trucks.
A warehousing operation or a shipping and receiving department often comprises a number of lift trucks that were purchased at different times and from different suppliers, and therefore, very little standardization can be found in the industry with regard to lift truck makes and models operated by a same company. Because of the uniqueness of each lift truck design, it has been difficult in the past for seat manufacturers to develop a standard model of seat suspension system that would be marketable to the industry in general, and that would be appropriate for easy installation on most models of lift trucks. It is this reason basically that has contributed to the development of a market demand for a better seat suspension system that is manufacturable as a common unit, and that is compatible to the conformations and limitations of most popular lift trucks.